The invention is directed to a switching network for a broadband communication system serving for the transmission of digital data signals, whereby the switching network is fashioned such that this is constructed of individual switching elements, that these switching elements respectively comprise a plurality of inputs as well as a plurality of outputs lower in number compared thereto, and such that the switching elements at least form a multi-stage funnel as a result of their connection to one another. Such a switching network is already disclosed by EP-B1-0 086 434.
Fischer, W., et al., xe2x80x9cA Scalable ATM Switching System Architecturexe2x80x9d IEEE Journal on selected areas of communications, Vol. 9, No. 8, Jan. 10, 1991, pp. 1299-1307, discloses a switching network for a digital broadband communication system wherein the switching network is fashioned such that this is constructed of individual switch elements, that these switch elements respectively comprise a plurality of inputs as well as a plurality of outputs smaller in number compared thereto, that the switch elements form at least one multi-stage funnel due to their connection to one another, and that the section for the assemblies of the switching network is selected such that four complete funnels are accommodated on each of the assemblies.
The aim in the realization of such communication systems is to realize the individual system components, thus including switching networks, with optimally low outlay, which has encountered difficulties in the meantime in practice in the realization of broadband switching networks with the demand of an increasing throughput rate as well as an increasing plurality of input lines and output lines. Given an assumed funnel structure for the switching network, for example, and proceeding from a selected data throughput of the employed components and assemblies, the outlay can increase more than quadratically when one wishes to enlarge the switching network with the same components by corresponding interconnection.
With respect thereto, Yoshimitsu, Arai, et al., xe2x80x9cMultigigabit Multichannel Optical Interconnection Modules for Asynchronous Transfer Mode Switching Systemsxe2x80x9d, Proceedings of the Electronic Components and Technology Conference, No. Conf. 43, Jan. 6, 1993, IEEE, pp. 825-830, discloses that a plurality of assemblies are connected to one another with the assistance of optical fiber connections via which information are optically transmitted with high bandwidth, high signal density, low attenuation and uninfluenced by electromagnetic interference. The plurality of the external connections of an assembly can thereby be reduced by the additional use of multiplexers.
An object of the present invention is to disclose a way of how a switching network of the species initially cited can be realized with economically justifiable costs.
In general terms the present invention is a switching arrangement for a broadband communication system serving for the transmission of digital data signals. The switching arrangement is constructed of individual switching elements. These switching elements respectively have a plurality of inputs as well as a plurality of outputs lower in number compared thereto. The switching elements form at least one multi-stage funnel as a result of their connection to one another. The section for the assemblies of the switching network is selected such that at least one complete funnel is accommodated on the respective assembly. Respectively two funnels are connected electrically parallel in that one of the respectively two funnels is arranged at both sides of the printed circuit board of the respective assembly.
Advantageous developments of the present invention are as follows.
The respective assembly has its external data inputs provided with unidirectionally designed optical/electrical transducers and also has its external data outputs provided with unidirectionally designed electrical/optical transducers.
The at least two funnels are connected electrically parallel at the input side following the optical/electrical transducers.
The respective electrical/optical transducer is fashioned such that data signals or, respectively, clock signals appearing on a line group of differential data lines and a differential clock line allocated thereto are first combined to form an electrical, serial multiplex signal that is subsequently electro-optically converted. The respective optical/electrical transducer is fashioned such that an optical, serial multiplex signal is converted into a plurality of electrical data signals and a clock signal allocated thereto and these data signals as well as the clock signal are forwarded via a line group of differential data lines and a differential clock line, the line group corresponding to the afore-mentioned line group.
The individual, differential data lines as well as the allocated differential clock line on the printed circuit board of the respective assembly are respectively fashioned as differential line pairs of coupled lines.
The respective differential line pair on the printed circuit board is fashioned as coupled tri-plate lines.
All line pairs of a line group are of the same length.
The optical/electrical transducers and electrical/optical transducers are fashioned as transducer modules. The transducer modules are mounted in edge plug-in sockets standing on the longitudinal edge of the respective assembly.
The optical/electrical transducers and electrical/optical transducers are connected to multiplex/demultiplex devices via appertaining optical lines.
The invention thereby yields the advantage that the transmission of data and clock signals within the communication system ensues electrically only within the respective switching network. By contrast thereto, the external signal transmission to or, respectively, from the respective switching network ensues in multiplex mode via optical connecting lines. In this way, the plurality of physical plug interfaces for the transmission of data signals and clock signals can be greatly reduced on the assemblies. Given, for example, a funnel having the structure 64/8 with 64 input ports, 8 output ports and 10 lines per port employed in the switching network, 720 (640+80) electrical plugs for signal inputs and signal outputs would be required in a purely electrical version in view of the technology of the electrical components employed. This number is reduced to 72 optical plug locations (optical fiber junctions), by contrast, when the assumed 10 lines per port are optically multiplexed, i.e. a reduction of plug locations of 10:1 ensues given the assumed example.